Kim the spider, who was trained to jump to help scientists study the mechanics of the jumping arachnid. Phtoo / University of Manchester
Kim the spider, who was trained to jump to help scientists study the mechanics of the jumping arachnid. Phtoo / University of Manchester
Spiders are notorious for making people jump.
But now scientists at the University of Manchester have turned the tables, training a jumping spider to leap between platforms on command so they could film its super-springy take-off and flight.
It wasn't easy. Several of the early spiders simply wandered away from the platforms, while others sat stubbornly still, baffled by the task of bounding on cue.
However, after several weeks of gentle encouragement, star arachnid Kim, finally began to spring from one ledge to the other, allowing scientists to record, monitor and analyse a spider's movement in high-resolution 3D for the very first time.
The aim of the study was to understand how jumping spiders modify their speed and trajectory when jumping long or short distances or leaping upwards.
A jumping spider can leap up to six times its body length from a standing start. The best a human can achieve is about 1.5 body lengths.
The researchers were anxious not to skew Kim's behaviour by tempting her to the other platform with food, as they would only have seen a predatory jump rather than recording the full range of her abilities.
Instead, over several weeks they placed Kim backwards and forwards between the ledges until she finally got the idea of jumping between them.
Not only does the new footage help to explain more about how the creatures manage the feat, but will help engineers to create an army of agile micro-robots capable of hunting pests, so that farmers would no longer need toxic pesticides.
Kim was taught to leap on command so her incredible jumping ability could be recorded in detail. Photo / University of Manchester / Dr Mostafa Nabawy
Dr Mostafa Nabawy, lead author of the study, said: "We could have used a cricket to tempt her to jump across the platforms but we could only have done that once a week because spiders don't eat that often, and we wanted to film different kinds of jumps, not just catching prey.
"There is a huge interest in developing jumping robots, but so far research has focussed on long distances. This research could allow robots to be created that jump shorter distances but are more accurate when they land.
"It could allow the development of robot spiders which are capable of hunting pests, so instead of using pesticides you could have an army of robotic spiders capable of targeting bugs."
Kim, who has since died, belonged to a species of jumping arachnid known as Phidippus regius, or "regal jumping spider" and was about 1cm long.
The team recorded her jumps using ultra-high-speed cameras, and used high resolution micro CT scans to create a 3D model of Kim's legs and body structure in unprecedented detail.
The spider's body was mapped using state-of-the-art scanners. Photo / University of Manchester
They found that to jump shorter, close-range distances she favoured a faster, lower trajectory, which uses up more energy, but minimises flight time. This makes the jump more accurate and more effective for capturing its prey.
But, if Kim is jumping a longer distance or to an elevated platform, perhaps to traverse rough terrain, she jumps in the most efficient way to reduce the amount of energy used.
Scientists have known for more than 50 years that spiders use internal hydraulic pressure to extend their legs.
Dr Bill Crowther, co-author of the study, explains: "Our results suggest that while Kim can move her legs hydraulically, she does not need the additional power from hydraulics to achieve her extraordinary jumping performance."
